Mystery Ranger Death Syndrome...

[Bronclow2]

The problem began with intermitant power loss, gradually getting worse. Now the truck is absolutly undrivable. I am at the end of my rope and need Help.

The truck idles OK, never stalls but fails to make any power at any throttle position. When it is first started it runs fine, and then less than a minute later is is compleely worthless. It is 1993 Ranger 4.0L Automatic.

Beginning with the basics I check fuel pressure, it was poor, so changed the pump and regulator. X

The a basic tune-up,Replaced plugs and wires. XX
it idles better. but Still makes NO Power.

I moved on to sensor testing, MAF and TPS result Good.
I Replaced the MAF (because I had one), Crank sens, Coil, and Ignition module. XXX

Now having good ignition and fuel, I look toward controls. I am now getting really deep over my head.
I pulled the injector plugs to compare bank 1 vs bank 2. Bank 2 exibited the problem much worse, so I tapped bank one in to its output. (1 output firing all 6 injectors) it made a differance but still not drivable. I rigged up a switch to open the injectors so that I could atleast narrow my focus. SO, when the truck is stumbling opening the injectors makes it take off like a rocket ship. this verifies that the injectors are not being controlled properly.

So where do I go from here? The ECM is far too expensive to take a gamble with; my experience with electronics is they work or don't work, no in the middle.

So the questions for the smart kids in the class is:
1) What does the ecm use for a trigger to fire the injectors?
2) What inputs are the "critical" ones : crank position(rpm), MAF and TPS?
3) what tests can I perform to confirm or dismiss an ECM issue?




So the reason I refered to this as Mystery Ranger Death Syndrome is that this is the third ranger I've had with a similar power loss issue that I can not fix.
The other 2 were both '87 2.9L Manual. I Replaced everything on them including wireharness and ECM no fix. Scrapped 1, used the other for parts.

 

[Sasquatch_Ryda]

Like just doesn't want to accelerate?

Have you checked for plugged exhaust? How do the plugs look?

Compression test?

 

[trail B2]

Do you think it could could be the senser in the camshaft synchronizer.Since it's main job is to control fuel injection.I've saved my but on weird stuff by cleaning every plug connection with electrical cleaner and chasing that with dielectric grease.Hopefully some of the pros will come up with better ideas.

 

[ShowUp817]

I had the same problem once and I replaced the alternator and replaced the alternator plug

 

[Bronclow2]

Like put it in drive and it coughs sputters pops and nothing else. but Idles great.

I covered the basics and verified that it is an EFI problem. I gave it more fuel -->it goes like hell.


Trail B2- I like your idea...I looked at that a whhile back ,but this truck has no cam syncronizer.... not equiped. Blank plug in the hole. I was surprised too. has no egr either who knew.

Showup, can you explain the alternator relationship? the charging system has always sucked on this truck it has a plow which doesnt help.

 

[adsm08]

Bad alternator = low available electrical power = problems with systems that run on electricity.

If you want to take a gamble on a part try the oxygen sensor. If you don't want to gamble on it, unplug the sensor and try driving it like that. If it's better, get a new sensor.

 

[Bronclow2]

Ok, I figured that was the general idea.

I monitered the voltage on the injectors during the fault and it never went below 11.6v mabee not great, but 9ish volts is the thumb rule for failing point.

Can a dead o2 really lead to a lean enough mixture that the vehicle won't even move?

Heres another question, Without a fancy scan tool how can I know if the system is in closed loop status? The system shouldn't use O2s in open status right?
Does disconnecting the coolant temp force open loop?

I'll try disconnecting...

 

[freedom5]

I agree with Jim Oaks - The O2 sensor can cause a lot of things. It should be changed every 60K. I'm not that familiar with the 4.0L but I finally resolved similar problems with my 2.9L. A lot of it was with the EGR system.

freedom5

 

[adsm08]

Ok, I figured that was the general idea.

I monitered the voltage on the injectors during the fault and it never went below 11.6v mabee not great, but 9ish volts is the thumb rule for failing point.

Can a dead o2 really lead to a lean enough mixture that the vehicle won't even move?

Heres another question, Without a fancy scan tool how can I know if the system is in closed loop status? The system shouldn't use O2s in open status right?
Does disconnecting the coolant temp force open loop?

I'll try disconnecting...

Unhooking the O2 sensor will force open loop. And yes, a faulty signal from the O2 sensor can cause any number of fuel related issues including running lean enough to burn valves and rich enough to look like a smoking diesel.

I agree with Jim Oaks

Ok, you and I have had this conversation on multiple previous occasions so try to keep up and understand this time because I'm getting tired of having it...

I AM NOT JIM OAKS!!!!!! I merely endorse him for the office of President of the United States.

Jim owns the site. I'm just a bum who hangs out here a lot.


Jim's profile

My profile


Jim's profile

My profile


Jim's profile

My profile

Picture of Jim:

Picture of me:

Jim is a former Ohio statie. He is a business man and entrepreneur who is married to a slamming hottie. He lives in Ohio.

I am a glorified grease monkey who is married to a nice girl who is just a bit overweight. I live in PA.

Got it yet?

- The O2 sensor can cause a lot of things. It should be changed every 60K. I'm not that familiar with the 4.0L but I finally resolved similar problems with my 2.9L. A lot of it was with the EGR system.

O2 sensors are usually given a 100K mile service interval. EGR may also play a role in your issue, if it has EGR, but it shouldn't be an intermittent problem and shouldn't allow the engine to idle at all. The symptoms sound to me like a failing O2 sensor. If unhooking the sensor makes it run better, I'd go with that.

 

[trail B2]

That's funny I was looking up and down the thread for a Jim Oaks post.At least now I know what adams o8 looks like 12,000 posts holy moly.


My B2 has a synchronizer on it's 93 4.0 so I figured yours would bronclow.Maybe mines a Cali. or something.

 

[adsm08]

That's funny I was looking up and down the thread for a Jim Oaks post.At least now I know what adams o8 looks like 12,000 posts holy moly.

Yeah, some months back when a bunch of us started adpoting the Jim/DG POTIS campaign logos he saw one of my posts and got it into his head that I am Jim. Despite me telling him on every occasion that I am not, he doesn't seem to get it.

Gonna change my Premium Member thing to "Not Jim" now.

 

[Rotagotideas]

O2 sensor

When you said unplugging the O2 sensor will force an open loop I was thinking what does it mean?
does it mean that it will run rich or will the injectors will run full open all the time?
my 408,000 km ( 250,000 mile ) 91 ranger with original drivetrain (2.9L) is rather low on power recently and been drinking a little more fuel (yes it could be wear yes it could be the ****ed lifter that ticks or the injectors being old or any number of things being a very high km truck) and I have owned this truck for 30,000km, no idea when the O2 sensor was last changed if ever. I do have a 160,000 km 2.9L motor sitting in my garage but can't really scarifice the time to swap it right now
so if I can get away with a $20 dollar fix for a month or two then I'll do it

 

[alwaysFlOoReD]

Open loop means the computer will run the engine using predetermined inputs rather than real time inputs. It usually does this until the o2 sensors are fully warmed up.
O2 sensors do get old and can't keep up with changing engine conditions, somewhat like the old-man-in-a-hat-sunday-driver-asshat-that-can't-get-out-of-his-own-way syndrome.

Richard

Richard

 

[Bronclow2]

Soooooo, I unplugged the O2's and it is currently working normal.

WTF?
My understanding is that O2 sensors are like a battery, they produce 0-1v based on the oxygen differential inside vs outside the pipe. 0v having no diferential makes means lean condition.

How then did both fail to indicating full rich? thats seems really fffffff'd up. I guess I'll save these bad ones for my perpetual motion machine.

I'm guessing that is probably what was wrong with the other trucks I had too sice I never changed the o2's on them either.

Thank you, adsm08(Mr. Not Jim) for the suggestion.

P.S I admire those of you who promptly run down to the parts store when the truck hits 59,999 miles to buy a new sensor. But I don't do that. I guess I should.

 

[adsm08]

O2 sensor failures will cause all sorts of screwy things to happen. I had a catalytic converter shell blow up once when the truck backfired due to an O2 that had literally fallen apart.

Another time I saw an Explorer that was doing all sorts of screwy stuff. Missing, no power, black smoke, intermittent CEL, all of it only after coasting for a while, mostly after going down big hills. Eventually I found that some joker had put a catalyst monitor sensor (the down stream O2) in the upstream sensor hole. They operate in different volt ranges and when it spiked up above 1V it was causing the computer to pull lots of fuel out of bank 2.